1. Field of the Invention
The present invention relates to an assembly which is capable of being fitted to a bottle having a vertical axis in order to form a dispensing head for a product, in particular a cosmetic composition, contained in the bottle.
2. Discussion of the Background
It relates in particular to an assembly for a bottle which comprises a neck with a vertical axis, which neck has a shoulder, the assembly comprising:                a ring which is capable of being engaged around the neck and which comprises profiles for retention on the neck which are capable of co-operating with the shoulder,        a fixed insert which is capable of being fitted to the bottle and which delimits a housing for receiving the ring.        
It is known to package perfumes, or other cosmetic compositions, in glass bottles which have, at the upper end thereof, a neck which is provided with an outer collar to which the dispensing head is fixed. The dispensing head is formed from another material, in particular a plastics material. This dispensing head may form a simple decorative hoop or carry a dispensing pump in order to take up the product which is contained in the bottle. The dispensing head may also comprise a control member which can be moved relative to a component which is fixed to the bottle, the control member being capable of activating a pump which has been retained beforehand by means of crimping around the neck of the bottle.
In order to mount the dispensing head on the bottle, it is known to interpose a ring which is capable of being engaged around the neck between the fixed body of the dispensing head, also referred to as the fixed insert, and the neck itself. The ring comprises profiles for retention on the neck which are capable of co-operating with a shoulder which is delimited below a collar which is provided at the end of the neck. The fixed insert delimits a housing for receiving the ring in which the ring is confined so that the profiles for retaining the ring on the neck are immobilised, making it impossible to release them.
The retention of the fixed insert on the ring is provided by means of friction. This is particularly the case for the arrangements described in documents EP 653 359, FR 2 897 851 and FR 2 856 994.
In other assemblies, described in particular in documents U.S. Pat. No. 4,773,553, U.S. Pat. No. 5,762,238 and FR 2 469 356, the retention of the insert on the ring is provided by means of resilient engagement owing to complementary profiles provided on the ring and the insert. This resilient engagement defines the relative position between the ring and the insert and consequently between the bottle and the head which is fitted to the bottle.
The arrangements described in this document are unsatisfactory in so far as, when the retention of the insert on the ring is provided by means of friction, it is necessary for the ring and the insert to have very precise manufacturing tolerances and the retention is not very reliable.
When the retention is provided by means of resilient engagement, the position of the insert on the bottle is predefined with the result that unsightly gaps are formed between the dispensing head and the bottle, owing to the significant manufacturing tolerances of the bottle which, since it is made from glass, cannot be produced with very precise dimensions.